Cleaning apparatus

ABSTRACT

A cleaning apparatus cleans an object to be cleaned by ejecting a cleaning agent from a nozzle. The cleaning apparatus includes a gas ejecting device for ejecting heated gas to a surface of the object to be cleaned. The gas ejecting device is configured to move to a position above the object to be cleaned when cleaning is performed, and retract from the object to be cleaned when cleaning is not performed. An ejection quantity of the heated gas is controlled when cleaning is performed and when cleaning is not performed.

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT

The present invention relates to a cleaning apparatus for cleaning and removing fine particles or organic substances on a surface of a hard disk medium, a silicon wafer, or the like.

It is necessary to completely clean a surface of a hard disk medium, a silicon wafer, or a glass plate of a liquid crystal display to remove fine particles or organic substances, so that irregularities of the surface is minimized and micromachining is applied.

An example of a cleaning apparatus for cleaning a surface of a silicon wafer or the like has been disclosed in Japanese Patent Publication (Kokai) No. 2003-1208. FIG. 5 is a view showing a structure of the cleaning apparatus disclosed in the publication. In FIG. 5, reference numeral 11 denotes a cylinder of CO₂ as a cleaning agent (hereinafter referred to as solvent), and CO₂ within the cylinder 11 is divided into a liquid portion 111 with a temperature T and a gas portion 112 with a pressure P_(O.) Reference numeral 12 denotes a heater for maintaining the cylinder 11 at a constant temperature. Reference numeral 13 denotes a pipe for taking out CO₂ gas. Reference numeral 14 denotes a pressure gage disposed in the pipe 13 for measuring a pressure within the pipe 13. A pressure within the pipe 13 is equal to the pressure P_(o) of the gas portion 112. Reference numeral 16 denotes a line filter attached to the pipe 13, and reference numeral 17 denotes an air operate valve attached to the pipe 13. The CO₂ cylinder, the line filter 16, and the air operate valve 17 are arranged in an order shown in FIG. 5.

Reference numeral 19 denotes a hard disk medium as an object to be cleaned, and a spindle 20 rotates the hard disk medium. Reference numeral 18 denotes a nozzle disposed with a predetermined gap d from the object 19 to be cleaned. The nozzle 18 is a double pipe type, in which CO₂ gas guided into the pipe 13 passes through an inner pipe, and N₂ gas passes through an outer pipe. Reference numeral 21 denotes an infrared heater for heating the object 19 to be cleaned. Reference numeral 22 denotes a purge pipe for ejecting N² gas. In FIG. 5, the pressure gage 14 measures a pressure within the pipe 13, and the heater 12 is controlled to maintain the pressure within the pipe 13 constant. Since CO₂ liquid and CO₂ gas coexist in the cylinder 11, the pressure P_(o) of the gas portion 112 corresponds to a saturation vapor pressure of the liquid portion 111 at the temperature T. The liquid temperature has a direct relationship relative to the saturation vapor pressure. Accordingly, when the heater 12 is controlled to adjust the temperature of the liquid portion 111, the saturation vapor pressure, i.e. the pressure within the pipe 13, can be controlled. For example, when the liquid temperature is adjusted at 22° C., the saturation vapor pressure becomes 6.0 MPa.

With the structure described above, it is possible to remove particles such as dusts from gas of the solvent (CO₂) through the line filter, and eject the solvent from the nozzle in a form of solid particles or droplets against the object to be cleaned, thereby removing particles or organic substances on the object. It is possible to change the solvent into solid particles or droplets by controlling a gap between the nozzle and the object to be cleaned. Accordingly, it is possible to select an optimum state of the solvent according to an extent of cleanness. Further, it is possible to easily remove particles such as dusts in the solvent through filtering, so that there is no need for an expensive and pure solvent, thereby reducing running cost.

However, the cleaning apparatus described above has the problems as follows. The infrared heater 21 is provided for heating the object 19 to be cleaned to a predetermined temperature, so that the infrared heater 21 generates particles such as dusts.

When CO₂ is ejected, an end of the nozzle 18 is rapidly cooled due to adiabatic expansion, and liquefaction occurs within a CO₂ passage as the temperature decreases. As a result, it is difficult to control generation of dry ice. To avoid this, the infrared heater 21 controls the temperature, but the generation of CO₂ may become unstable since the temperature of the nozzle 18 is not independently controlled.

In view of the problems described above, an object of the present invention is to provide a cleaning apparatus capable of cleaning while reducing dusts, and preventing dew condensation of an object to be cleaned due to CO₂ sprayed thereto and condensation of CO₂ within a pipe.

Further objects and advantages of the invention will be apparent from the following description of the invention.

SUMMARY OF THE INVENTION

To attain the objects described above, according to a first aspect of the invention, a cleaning apparatus cleans an object to be cleaned by ejecting a cleaning agent from a nozzle, and includes gas ejecting means for ejecting heated gas to a surface of the object to be cleaned. The ejecting means is configured to move to a position above the object to be cleaned when cleaning is performed, and retract from the object to be cleaned when cleaning is not performed. An ejection quantity of the heated gas is controlled when cleaning is performed and when cleaning is not performed.

According to a second aspect of the invention, in the cleaning apparatus according to the first aspect, the gas ejecting means has a plurality of jet holes, and the heated gas at a predetermined temperature is ejected through the plurality of jet holes.

According to a third aspect of the invention, in the cleaning apparatus according to one of the first and second aspects, the gas ejecting means has one end thereof supported by a supporting member, and is disposed at a predetermined interval from the surface of the object to be cleaned such that the gas is ejected toward the surface of the object to be cleaned.

According to a fourth aspect of the invention, in the cleaning apparatus according to one of the first to third aspects, the jet holes of the gas ejecting means are at a predetermined angle with respect to the surface of the object to be cleaned.

According to a fifth aspect of the invention, in the cleaning apparatus according to the fourth aspect, the gas ejecting means is disposed between a center and a circumference of the object to be cleaned, and the jet holes are arranged with at least two directions, i.e. a direction perpendicular to the surface of the object to be cleaned and an inner circumferential direction or an outer circumferential direction.

According to a sixth aspect of the invention, in the cleaning apparatus according to one of the first to fifth aspects, a filter is provided for cleaning gas.

According to a seventh aspect of the invention, in the cleaning apparatus according to one of the third to sixth aspects, the supporting member, the filter and a heater for heating gas are disposed within an environmental chamber.

According to an eighth aspect of the invention, in the cleaning apparatus according to one of the third to seventh aspects, at least one of the supporting member and the filter has a temperature control mechanism.

According to a ninth aspect of the invention, in the cleaning apparatus according to one of the third to eighth aspects, the gas ejecting means supported by the supporting member includes at least two portions disposed on the surface of the object to be cleaned with a center thereof in between.

According to a tenth aspect of the invention, in the cleaning apparatus according to the ninth aspect, the gas flows into the at least two portions of the gas ejecting means from one gas source.

According to an eleventh aspect of the invention, in the cleaning apparatus according to one of the second to tenth aspects, solvent ejecting means is mounted in the vicinity of a center of the at least two portions of the gas ejecting means supported by the supporting means. The gas ejecting means and the solvent ejecting means are driven together.

According to a twelfth aspect of the invention, in the cleaning apparatus according to one of the first to eleventh aspects, the solvent ejecting means comprises temperature control means for maintaining the solvent ejecting means at a temperature equal to or higher than a dew point of the solvent.

According to a thirteen aspect of the invention, in the cleaning apparatus according to one of the first to twelfth aspects, a gas jetting hole is formed on an outer circumference of a nozzle provided in the solvent ejecting means for ejecting the gas.

According to a fourteenth aspect of the invention, in the cleaning apparatus according to one of the first to thirteenth aspects, the solvent ejecting means has a rod shape, and is provided with a wedge-shaped surface inclined in a longitudinal direction relative to the surface of the object to be cleaned.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a structure of an essential part of a cleaning apparatus according to an embodiment of the present invention;

FIGS. 2(a) to 2(c) are views showing solvent ejecting means according to the embodiment of the present invention, wherein FIG. 2(a) is a sectional view thereof, FIG. 2(b) is a side view thereof, and FIG. 2(c) is an enlarged sectional view of FIG. 2(b);

FIGS. 3(a) to 3(c) are views showing the solvent ejecting means according to another embodiment, wherein FIG. 3(a) is a sectional view thereof, FIG. 3(b) is a side view thereof, and FIG. 3(c) is an enlarged sectional view of FIG. 3(b);

FIGS. 4(a) to 4(c) are views showing the solvent ejecting means ejecting dry ice (CO₂) according to the embodiment of the present invention, wherein FIG. 4(a) is a front view thereof, FIG. 4(b) is a side view thereof, and a FIG. 4(c) is a perspective view thereof;

FIG. 5 is a view showing a structure of a conventional cleaning apparatus.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereunder, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a view showing a structure of an essential part of a cleaning apparatus according to an embodiment of the present invention. In FIG. 1, an area A enclosed by a phantom line is a environmental chamber, in which a heat insulting material (not shown) prevents heat exchange with outside. The environmental chamber A contains a heater block 4, a filter 3, and a supporting member 2. Reference numeral 1 denotes pipes as gas ejecting means having closed one ends and the other ends fixed to the supporting member (manifold) 2. As shown in FIG. 1, each of the pipes 1 is disposed between a center and a periphery of an object 19 to be cleaned. It is preferred that four pipes 1 are provided on both sides of the object 19 to be cleaned for preventing dew condensation on the object 19 to be cleaned. However, one pipe 1 may be provided as far as dew condensation can be prevented.

Each of the pipes 1 is provided with series of holes 1 a and 1 b in the longitudinal direction thereof. The holes 1 a and 1 b are formed with regular intervals in between at a predetermined angle relative to the surface of the object 19 to be cleaned. Specifically, the holes 1 a are formed in a direction perpendicular to the surface of the object 19 to be cleaned, and the holes 2 a are formed with an angle of 45

degrees relative to the center of the object 19 to be cleaned.

The supporting member 2 has a branched hole 2 a, and the other ends of the two pipes 1 are airtightly fixed to both ends of the branched hole 2 a. A pipe 3 a communicating with an outlet of the filter 3 is connected to a predetermined location of the branched hole 2 a. A pipe 4 a is connected to an inlet of the heater block 4 for guiding N₂ gas, and a pipe 4 b connected to the inlet of the filter 3 is connected to the outlet of the heater block 4. The pipe 4 a for guiding N₂ gas is configured such that N₂ gas flows in from two directions. That is, a small quantity of N₂ gas constantly flows into the pipe 4 a from an inlet of a constant lead-in pipe 6 a, and a relatively large quantity of N₂ gas flows into the pipe 4 a from an ejection lead-in pipe 6 b via an air operate valve 5 during cleaning.

Reference numeral 8 denotes rod-shaped CO₂ ejecting means formed of a high thermal capacity metal block 8 a having, for example, 50 mm in length and 15 mm in side. The CO₂ ejecting means has one end fixed to the supporting member 2 and the other end provided with a nozzle 8 b having a jet hole of about 0.3 mm, for example.

FIGS. 2(a) to 2(c) are views showing the CO₂ ejecting means 8 according to the embodiment, in which FIG. 2(a) is a sectional view thereof, FIG. 2(b) is a side view thereof, and FIG. 2(c) is an enlarged sectional view of FIG. 2(b). In FIGS. 2(a) to 2(c), reference numeral 8 c denotes a CO₂ passage for guiding CO₂ as a solvent, and reference numeral 8 d denotes an N₂ passage for guiding N₂ gas. It is configured such that N₂ gas led into the N₂ passage 8 d is ejected from the periphery of the nozzle 8 b.

The nozzle 8 b is fabricated as a separate part, and is fixed to an end of the metal block 8 a by press-fitting, welding, or the like. Reference numeral 8 e denotes temperature control means having a temperature sensor and a temperature control circuit (not shown).

FIGS. 3(a) to 3(c) are views showing the ejecting means 8 according to another embodiment, in which FIG. 3(a) is a sectional view thereof, FIG. 3(b) is a side view thereof, and FIG. 3(c) is an enlarged sectional view of FIG. 3(b). In FIGS. 3(a) to 3(c), reference numeral 8 f denotes a CO₂ passage for guiding CO₂ as a solvent, and reference numeral 8 e denotes temperature control means having a temperature sensor and a temperature control circuit (not shown). The CO₂ ejecting means 8 shown in FIGS. 3(a) to 3(c) differs from the CO₂ ejecting means 8 shown in FIGS. 2(a) to 2(c) in that the N₂ passage 8 d for N₂ gas ejection (refer to FIGS. 2(a) to 2(c)) is not provided, and a wedge-shaped part 9 and a relief part 10 are provided on a surface opposite to the surface of the object 19 to be cleaned.

FIGS. 4(a) to 4(c) show a flow of CO₂ when the CO₂ ejecting means 8 (metal block 8 a) shown in FIGS. 3(a) to 3(c) ejects CO₂. FIG. 4(a) is a front view thereof, FIG. 4(b) is a side view thereof, and a FIG. 4(c) is a perspective view thereof. As is apparent from FIGS. 4(a) to 4(c), CO₂ jetted from the nozzle 8 b smoothly flows without rebounding between the nozzle 8 b and the metal block 8 a.

Referring to FIG. 1, the supporting member 2, the filter 3, the heater block 4, the CO₂ ejecting means 8, and the pipes 1 are provided in the environmental chamber A indicated by the phantom line, and are driven integrally with each other. When the object 19 to be cleaned is cleaned, the environmental chamber A moves in an arrow direction B so as to seek the object 19 to be cleaned. As the object 19 to be cleaned is sought, CO₂ is ejected from the nozzle 8 b. In synchronism with timing of the CO₂ ejection, the air operate valve 5 is opened, so that a large quantity of N₂ gas is ejected from the ejection lead-in pipe 6 b.

When the cleaning is completed, the environmental chamber A retracts in an arrow direction C so as to attach/remove the object 19 to be cleaned. Even when the environmental chamber A retracts, a small quantity of N₂ gas heated to a predetermined temperature is jetted into the pipes 1 via the constant lead-in pipe 6 a, the heater block 4, the filter 3, and the supporting member 2 in this order, so that the pipes 1 is maintained at a predetermined temperature.

During the cleaning, N₂ gas from the jet holes 1 a perpendicular to the object 19 to be cleaned heats mainly the surface of the object 19 to be cleaned. Similarly, N₂ gas from the jet holes 1 b formed inwardly with an angle of 45

degress heats evenly the whole area of the object 19 to be cleaned. It should be noted that temperature control means provided in the heater block 4 and the filter 3 maintains N₂ gas at a predetermined temperature.

As described above, the CO₂ ejecting means is shown in FIGS. 2(a)-2(c) and 3(a)-3(c). The CO₂ ejecting means shown in FIGS. 2(a)-2(c) emits CO₂ gas from the CO₂ passage 8 c via the nozzle 8 b, while the CO₂ ejecting means shown in FIGS. 3(a)-32(c) ejects N₂ gas through the holes formed in the periphery of the nozzle 8 b. N₂ gas is ejected from the periphery of the nozzle 8 b for the following reason. When CO₂ gas is ejected from the nozzle 8 b, CO₂ gas is cooled by adiabatic expansion and a temperature around the periphery of the nozzle 8 b is lowered. Therefore, the temperature of the entire nozzle block is lowered below the liquefying temperature of CO₂ gas (22° C. at 6 MPa). Accordingly, CO₂ gas liquefies in a pipe section of the nozzle block, and is ejected as liquid. As a result, generation of dry ice becomes unstable, and it is difficult to control the generation of dry ice. To prevent this phenomenon, the temperature control means 8 e controls the temperatures of CO₂ and N₂ gas.

In the embodiment shown in FIG. 3, the CO₂ ejecting means 8 omits ejection of N₂ gas, and has the nozzle 8 b simplified. The temperature control means 8 e heats the entire high thermal capacity metal block 8 a so that it can be kept at a temperature equal to or higher than the liquefying temperature of CO₂.

With this arrangement, it is not necessary to eject N₂ gas for purging as shown in FIG. 2. Accordingly, it is possible to omit a filter and valve, thereby reducing a size and weight of the entire system. Further, it is not necessary to join the nozzle 8 b, thereby making the nozzle 8 b simple.

In the present embodiment, the side of the CO₂ ejecting means facing the object 19 to be cleaned is formed in a wedge-shape. As a result, it is possible to smoothly clean the object 19 to be cleaned without dry ice jetted from the nozzle 8 b rebounding between the metal block 8 a and the nozzle 8 b. It should be noted that the wedge-shaped part 9 may be provided in the CO₂ ejecting means 8 shown in FIG. 2 as well.

The present invention has been described in detail with reference to the specific embodiments for purposes of explanation and illustration. Accordingly, it will be apparent to a person skilled in the art that certain changes and modifications may be practiced within the scope of the invention. For example, in the embodiments described above, the CO₂ ejecting means has a rectangular shape, and the pipes are used as the N₂ ejecting means, but they may have an arbitrary shape. Further, the temperature control means for heating is provided in both the filter 3 and the heater block 4, and may be provided in one of them. N₂ gas is used for heating, and dry air or the like may be used. The scope of the present invention is defined by the claims, and includes modifications and variations within the scope of the present invention.

As described above, the following effects can be obtained according to the present invention. In the first aspect of the invention, the cleaning apparatus ejects the cleaning agent from a nozzle to clean an object. The cleaning apparatus includes the gas ejecting means for ejecting heated gas to a surface of the object to be cleaned. The ejecting means is configured to move to a position above the object to be cleaned when the cleaning is performed, and retract from the object to be cleaned when the cleaning is not performed. An ejection quantity of the heated gas is controlled when the cleaning is performed and is not performed. Therefore, the cleaning apparatus can perform more satisfactory cleaning by reducing dust sources and preventing dew condensation caused by CO² jetted onto the object to be cleaned.

In the second to fifth aspects of the invention of, the gas ejecting means comprises a plurality of jet holes from which gas heated to a predetermined temperature is ejected, and is disposed at a predetermined interval above the surface of the object to be cleaned. The jet holes are formed with at least two directions, i.e. a direction perpendicular to the surface of the object to be cleaned and an inner circumferential direction or an outer circumferential direction. Therefore, it is possible to prevent temperature irregularities on the surface of the object to be cleaned as well as the thermal cleaning thereof.

In the sixth aspect of the invention, the filter it provided for cleaning gas, thereby eliminating contamination on the object to be cleaned due to heated gas.

In the seventh and eighth aspects of the invention, the supporting member and the filter as well as the heater for heating gas are disposed within the environmental chamber. At least one of the supporting member and the filter includes the temperature control mechanism. Therefore, it is possible to accurately control the temperature of N² gas supplied to the gas ejecting means.

In the ninth to eleventh aspects of the invention, at least two gas ejecting means supported by the supporting member are disposed on the surface of the object to be cleaned across the center thereof. The single gas source supplies gas into the two gas ejecting means, and the solvent ejecting means is mounted in the vicinity of a center of the two gas ejecting means supported by the supporting means, and is driven integrally with the gas ejecting means. Therefore, it is possible to simplify the entire structure of the cleaning apparatus.

In the twelfth aspect of the invention, the solvent ejecting means for ejecting solvent is provided with the temperature control means for controlling solvent at a temperature equal to or higher than a dew point. Accordingly, it is possible to accurately control the temperature of CO₂.

In the thirteenth aspect of the invention, the gas jetting holes for jetting gas are formed on an outer circumference of the nozzle provided in the solvent ejecting means. Accordingly, it is possible to accurately control the temperature of CO₂.

In the fourteenth aspect of the invention, the solvent ejecting means has a rod shape and a wedge-shaped surface inclined in a longitudinal direction thereof and facing the surface of the object to be cleaned. Accordingly, it is possible to smoothly clean the object to be cleaned without ejected dry ice rebounding between the nozzle and the metal block.

The disclosure of the specification and drawings explained in Japanese Patent Application No. 2003-156321 filed on Jun. 2, 2003 is hereby incorporated.

While the invention has been explained with reference to the specific embodiments of the invention, the explanation is illustrative and the invention is limited only by the appended claims. 

1. A cleaning apparatus for cleaning an object with a cleaning agent, comprising: gas ejecting means for ejecting heated gas to a surface of the object, said ejecting means moving to a position above the object when cleaning is performed and retracting from the position above the object when cleaning is not performed, and means for controlling a quantity of the heated gas when cleaning is performed and is not performed, said controlling means being connected to the gas ejecting means.
 2. A cleaning apparatus according to claim 1, wherein said gas ejecting means has a plurality of jet holes, and ejects the heated gas with a predetermined temperature through the plurality of the jet holes.
 3. A cleaning apparatus according to claim 1, further comprising a supporting member for supporting one end of the gas ejecting means to be disposed at a position with a predetermined distance from the surface of the object so that the heated gas is ejected toward the surface of the object.
 4. A cleaning apparatus according to claim 2, wherein said jet holes of the gas ejecting means are arranged with a predetermined angle relative to the surface of the object.
 5. A cleaning apparatus according to claim 2, wherein said jet holes are arranged with at least two directions including a direction perpendicular to the surface of the object and an inner circumferential direction or an outer circumferential direction of the object.
 6. A cleaning apparatus according to claim 1, further comprising a filter for cleaning the heated gas.
 7. A cleaning apparatus according to claim 3, further comprising a heater for heating the heated gas, a filter for cleaning the heated gas and an environmental chamber for retaining the heater, the filter and the supporting member.
 8. A cleaning apparatus according to claim 7, wherein at least one of said supporting member and said filter includes a temperature control mechanism.
 9. A cleaning apparatus according to claim 3, wherein said gas ejecting means includes at least two portions supported by the supporting member to be disposed above the surface of the object with a center of the object therebetween.
 10. A cleaning apparatus according to claim 9, further comprising one gas source for supplying the heated gas into the at least two portions.
 11. A cleaning apparatus according to claim 9, further comprising solvent ejecting means disposed between the two portions, said solvent ejecting means being driven together with the gas ejecting means.
 12. A cleaning apparatus according to claim 11, wherein said solvent ejecting means includes temperature control means for maintaining solvent at a temperature equal to or higher than a dew point thereof.
 13. A cleaning apparatus according to claim 11, wherein said solvent ejecting means includes a nozzle having a gas jetting hole at an outer circumference thereof for ejecting gas.
 14. A cleaning apparatus according to claim 11, wherein said solvent ejecting means has a rod shape and a wedge-shaped surface inclined in a longitudinal direction thereof to face the surface of the object. 